Method and apparatus for casting metals



July El R MOROQQ ,4415,@

METHOD AND APPARATUS FOR CASTING METALS Filed March 28, 1945 2 Sheets-Sheet l I NVEN TUE- w pH/L /P Mopoo,

Juliy 2, 194, P. MOROCO METHOD AND APPARATUS FOR CASTING METALS Filed March 28, 1.945

2 Sheets-Sheet 2 INVENTUE PH/L MOROCO,

Patented July 20, 1948 METHOD AND APPARATUS FOR CASTING ME ALS Philip Moroco, Farrell, Pa., assignor to Carnegie- Illinois Steel Corporation, a corporation of New Jersey Application March 28, 1945, Serial No. 585,230

s- Claims. 01. 22-116) This invention relates to a method and apparatus for casting metals and is particularly adapted for replacing a broken tooth in a gear. Since large gears and pinions are expensive, it is desirable to replace the broken tooth and continue using the gear instead of scrapping it. The teeth of used gears are worn unevenly across their faces and it is therefore desirable to replace the broken tooth with a tooth having the contour of other teeth in the gear instead of the contour of the original tooth. It is common to replace such teeth by means of the well known Thermit Process. The process most commonly used prior to my invention consisted of making two sand cores the shape of the recess between two worn teeth, placing a core on each side of the tooth to be replaced, pouring wax into the mold formed by the cores to make a wax pattern of the tooth, placing a sand mold about the wax tooth, heating the gear to a temperature at which the wax melts, causing it to flow out of the mold and then pouring the molten metal into the mold. While making the wax pattern, the gear is in a horizontal position with the tooth to be replaced at the top, but the metal is poured into the mold with the gear in a vertical position. This method, while fairly satisfactory, is expensive, slow, and the finished tooth is relatively rough.

It is an object of my invention to provide a relatively inexpensive and accurate method of replacing a broken gear tooth or the like.

Another object is to provide a jig for use in carrying out my method.

These and other objects will be more apparent after referring to the following specification and attached drawings, in which:

Figure 1 is a sectional view showing the jig in place over a good tooth;

Figure 2 is a sectional view taken on the line II-II of Figure 1;

Figure 3 is a sectional view showing the jig in place over a tooth to be cast;

Figure 4 is a sectional view taken on the line IV-IV of Figure 1;

Figure 5 is a sectional view showing the jig removed and the wax tooth sand-packed ready for pouring;

Figure 6 is an end view of the spacer box;

Figure 7 is an elevation of the anchor plate;

Figure 8 is an end view of the anchor plate of Figure '7;

Figure 9 is an elevation of the jig saddle;

Figure 10 is a top plan view of Figure 9;

Figure 11 is a top plan view of the tooth extension; and

Figure 12 is a cross sectional view of Figure 11 taken between the cross bars.

Referring more particularly to the drawings, the reference numeral 2 indicates a gear having a broken tooth which is to be replaced. In the gear shown, thereis a shroud 4 at each end of the teeth. The first step in replacing the tooth is to cut off the tooth to its base and cut a slot 6 in the body of the gear, the cutting extending the entire lengths of the tooth and through the shroud on the free side of the pinion. The gear is supported with its axis in a horizontal position and a jig 8 is placed over a good tooth ID at the top of the gear. The jig includes two spacer boxes l2, each of which is of substantially triangular cross section and whose length is approximately the same as that of the tooth. Spaced apart reinforcing ribs I4 are welded to the inside of the side walls It which are provided with bolt holes I8. The end walls 20 are also provided with bolt holes 22 preferably of the same size as holes 18. Th top of the side walls Hi may be bent over at 24 to facilitate handling of the spacer box. An anchor plate 26 is fastened to each side of each spacer box and has approximately the same shape as the side of the spacer box except that it need not extend to the bottom thereof. Bolt holes 28, spaced the same as holes I8, are provided in the anchor plate. Welded to the outside of plate 26 is a bar 30 having a plurality of holes 32 therein. Below the bar 30 are a plurality of bent bars 34 welded to the plate '26, there being an opening 35 between the plate and the bar as shown in Figure 8. The spacer boxes are-adapted to be fastened to end saddles 36, each of which consists of two flanged plates 31 fastened together by means of bolts extending through holes 38 in the flanges 40. The bottom of the plates 31 have the same curvature as the shroud 4. Three bolt holes 4! are provided in each of the plates 31 and are spaced in the same manner as holes 22 in spacer box l2.

In assembling thejig to obtain an impression of tooth III, a spacer box I2 is placed in the recess 42 on each side of tooth l0 with an anchor plate 26 bolted to each side of each spacer box. A liner 44, having holes spaced in the same manner as holes l8 and 28 to permit passage of the fastening bolts therethrough, is provided between each spacer box and the anchor plate facing tooth l0. On top of the tooth II] is placed an extension 46 which is made of two quarter-round bars 48 fastened together by means of cross bars 50. The jig saddles 36 are fastened to each end of the spacer box by means of bolts extending through holes 22 and 4|. In bolting the two parts of the saddle together, a combined spacer plate and extension keeper 52 is inserted between the flanges 40 of the saddles. The spacer plate 52 is U-shaped as shown in Figure 2, and has slots 54 in the bottom thereof which receive bars 50 to hold the tooth extension 46 in place. Plate 52 is provided with holes 56 at each end for passage of the bolts holding the two parts of the saddle together. It will be seen that the saddles 36 rest on the shrouds 4 at each end of the teeth, this positioning the Jig in the desired vertical position. After the jig is arranged in the desired position, asbestos putty 58 is packed solid around the bottom of the spacer boxes l2 to prevent leakage of babbitt which is poured into the ji around the spacer boxes I! to fill the recess 42 on each side of tooth I0. In other words, the babbitt and the spacer boxes together completely fill the recesses 42 on both sides of the good tooth, the babbitt extending completely to the teeth on each side of the good tooth. The babbitt flows into the holes 32 of bar 30 and into openings 35 and around the bars 34, thus anchoring the babbitt 58 to the plates 28. After the babbitt solidifies, the spacer boxes, anchor plates, and end saddles are separated and removed from around tooth ill.

The gear 2 is then rotated until the tooth to be replaced reaches the top and the spacer boxes i2 are placed in the recesses 60 on each side of the tooth to be replaced. The anchor plates are fastened to the spacer boxes in the same manner as described above except that the liners 44 are removed. The spacer boxes are also fastened to the saddles 36 in the same manner as described above except that a filler 62 of the same width as flanges 40 is inserted between the flanges 40 in place of the plate 52. The extension 46 having been removed, there is an opening at the top of the mold through which wax is poured to form a wax pattern SI of the tooth to be replaced. The extension 46 was used in making the mold in order that enough wax may be poured to take care of shrinkage. The liners 44 are removed before pouring the wax in order to make the wax tooth enough larger than the good tooth to take care of the contraction of the molten metal. While I.

have referred to wax in my description it will be understood that other materials of similar characteristics could be substituted therefor and it is in this respect that the term is used herein.

The process then proceeds as formerly, the gear being placed in a vertical position with the free side up and sand 64 is packed around the wax tooth as shown in Figure 5. The gear is heated up to between 1200 and 1500 F. which melts the wax and causes it to flow out of the heating gate after which the molten metal is poured into the mold. In heating the gear, a brick furnace is constructed around the exposed part of the gear and a burner is placed at the bottom thereof. The initial heating is slow so that no internal strains are produced. After the gear has been thoroughly soaked with heat, the fire can be increased until the gear is heated up to the aforesaid temperature. (See Thermit Mill and Foundry Practice, published by Metal 8: Thermit Corp., and Thermit Welding, published in June 1927 by the American Welding Society.)

In place of babbitt, other relatively low melting point materials may be used to obtain the impression of the good tooth and other materials other than wax may be poured into the babbitt mold. However, these are the two materials commonly used and it is apparent that the material used to obtain the impression of the good tooth must .primary importance when replacing parts which must be made to close tolerances, such as cam surfaces and gear teeth.

While one embodiment of my invention has been shown and described, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. The method of replacing a broken tooth in a gear comprising placing a spacer box in the valley on each side of a good tooth, fastening anchor plates to each side of each spacer box with a liner therebetween, fastening each end of each of the spacer boxes to end saddles, casting a low melting point material onto the anchor plates to fill the valleys on each side of the good tooth to form a mold, removing the spacer boxes,

anchor plates, molds and end saddles, placing the spacer boxes in the valleys on each side of the tooth to be replaced, fastening anchor plates with the molds thereon to each side of each spacer box with the liners removed, fastening each end of each of the spacer boxes to the end saddles, pouring wax into the mold to form a pattern of a good tooth, removing the spacer boxes, anchor plates, molds and end saddles from the wax tooth, packing sand around the wax tooth to form a sand mold, melting out the wax tooth by heating the gear, and then pouring molten metal into the sand mold. V

2. A. jig for use in obtaining a mold for a gear tooth which comprises, spacer boxes, one adapted to be placed in the valley on each side of a ear tooth, an anchor plate fastened to each side of each spacer box, a liner between each of the anchor plates adjacent the gear tooth and the spacer box, and end saddles fastened to the ends of the spacer boxes.

3. A jig for use in obtaining a mold for a gear tooth which comprises, spacer boxes, one adapted to be placed in the valley on each side of ,a gear tooth, an anchor plate fastened to each side of each spacer box. a liner between each of the anchor plates adjacent the gear tooth and the spacer box, end saddles fastened to the ends of the spacer boxes, and an extension adapted to be placed on top of the tooth.

4. A jig for use in obtaining a mold for a gear tooth which comprises, spacer boxes, one adapted to be placed in the valley on each side of a gear tooth, an anchor plate fastenedto each side of each spacer box, a liner between each of the anchor plates adjacent the gear tooth and the spacer box, end saddles fastened to the ends of the spacer boxes, each end saddle being made of two parts fastened together at the center of the tooth, and means extending between the end saddles and fastened thereto for holding the tooth extension in place.

5. The method of replacing a broken part of an article comprising placing a separable jig with at least one linertherebetween over an unbroken part which is similar to the broken part. castin a low melting oint material onto the jig around the unbroken part to form a mold, separating the parts of the separable jig, placing the jig and the mold over the broken part with the liner removed therefrom, pouring wax into the mold to form a pattern of an unbroken part, removing the jig and the mold from the wax pattern, packing sand around the pattern to form a sand mold, melting out the wax and pouring molten metal into the sand mold.

6. The method of replacing a broken part of an article comprising placing a spacer box on each side of an unbroken part which is similar to the broken part, fastening anchor plates to the side of each of the spacer boxes adjacent the unbroken part with a liner therebetween, fastening the spacer boxes together, casting a. low melting point material into the anchor plates to fill the space between the unbroken part and the spacer boxes to form a mold, removing and separating the spacer boxes and anchor plates, placing the spacer boxes on each side of the broken part, fastening the anchor plates and the molds to the side of each of the spacer boxes adjacent the broken part with the liners removed, fastening the spacer boxes together, pouring wax into the mold to form a pattern of an unbroken part, removing and separating the spacer boxes and anchor plates with the mold thereon from the wax pattern, packing sand around the wax pattern to form a sand mold, melting out the wax pattern, and pouring molten metal into the sand mold.

7. The method of replacing a broken tooth in a gear comprising placing a separable jig with at least one liner therebetween over a good tooth, casting a low melting point material onto the jig around the good tooth and to the teeth on each side of the good tooth to form a mold, removing the liner from between the parts of the separable jig, placing the jig and the mold over anchor plate adjacent the good tooth, fastening the end saddles together, casting a low melting point material onto the anchor plates to fill the valleys on each side of the good tooth to form a mold, removing and separating the spacer boxes and anchor plates, placing the spacer boxes in the valleys on each side of the tooth to be replaced, fastening the anchor plates and the molds to each side of each spacer box with the liners removed, fastening the spacer boxes together, pouring wax into the mold to form a pattern of a good tooth, removing the spacer boxes and anchor plates with the moldthereon from the wax pattern, packing sand around the wax pattern to form a sand mold, melting out the wax pattern, and then pouring molten metal into the sand mold.

PHILIP MOROCO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 356,031 Currie Jan. 11, 1887 1,508,800 Mattice Sept. 16, 1924 2,200,449 Jungersen May 14, 1940 40 1,530,344 Begtrup Mar. 17, 1925 

